First post, by CelGen
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Shouldn't really say "another" as it's my first post but it seems the topic pops up every so often here. Yes I've lurked a bit.
Annnnyways, I'm generally not too fond of building rigs where I'm dealing outside the usual 25/33mhz FSB range but this time I'm forced. I'm currently working on upgrading (and repairing....) an IBM PS/2 model 95 that came into my ownership. Originally it had the Type 2 CPU complex which used a 25mhz SX and was further upgraded with a 50mhz DX2 however with no L2 it's still not much of an upgrade. I'm replacing the entire complex with the newer Type 3 complex which gives me a 50mhz DX but also gives me 256k of L2 and the unfortunate task of trying to source 40-bit ECC DRAM....
I've hated working with the 50mhz 486 machines so much that I really don't know what to do for upgrading the CPU. The Type 3 complex has a 50mhz FSB and because the Am5x86-P75 (Kingston Turbochip packaging) has been repeatedly been shown to work at 150mhz I assumed that removing Pin R17 (which noted here should set the multiplier at x3 instead of x4) I would be able to at least POST but contrary to others I can't get it to POST. I can however get the chip to reliably work in the old Type 2 complex which has a 25mhz FSB with no modifications though at that point we are underclocking and on the wrong board.
OP Edited: Major rewrite to clear up things I said while half awake
"It's science. I ain't gotta explain sh*t"